Method and device using CCD-based low noise parametric amplifier

Abstract

Embodiments of the present invention provide a device with an integrated low-noise parametric amplifier using a CCD-based structure with minimal noise gain. In one embodiment, a device which may be used for monitoring and / or diagnosing a human or an animal body comprises a CCD-based device including a first gate forming a first capacitor and a second gate forming a second capacitor, the first capacitor having a surface area larger than a surface area of the second capacitor; and a controller configured to input a signal to the CCD-based device; convert the input signal into a charge packet having a voltage associated therewith; transfer the charge packet from the first capacitor to the second capacitor of the CCD-based device, the voltage associated with the charge packet being multiplied by a ratio of the surface area of the first capacitor divided by the surface area of the second capacitor; and produce an amplified output signal from the multiplied voltage.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Patent Application No. 60 / 575,528, filed May 28, 2004, the entire disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] Charge-coupled devices (CCDs) are well known for their use as sensors in digital imaging and video processing. Specifically, they consist of an array of linked or coupled capacitors, where sampled values of an analog signal are stored as charge. The charge can be shifted along the capacitor array by an applied or clock voltage, thus propagating the charge through the array. The charge is eventually transferred from the CCD as an output signal. Amplification of the output signal is usually required, however, because the signal may be too weak to be accurately read or used in a later stage, or because subsequent operations require a certain threshold voltage. An off-chip amplifier is conventionally used for this process, connect...

AI Technical Summary

Benefits of technology

[0005] Embodiments of the present invention provide a device with an integrated low-noise parametric amplifier using a CCD-based structure with minimal noise gain. The CCD-based structure may be integrated into an IC chip for a medical monitoring and / or diagnostic device. The amplification of the signal is achieved by using a method of capacitance modulation by varying the surface area of the capacitor plates which are used to convey the charge rather than conventional amplification techniques utilizing transistor transconductance. The corresponding voltage gain introduces very little noise, because no additional sources of noise such as active components are introduced in the charge amplification process while shifting the charge from the larger CCD gate to the smaller CCD gate. The CCD capacitance ratio approach is essentially forming a varactor with a very large turn-down ratio.

[0007] Advantageously, a CCD-based amplifier using the present approach can be implemented in a smaller area than a comparable CMOS process. The gain obtained by the method of this invention can greatly relax noise requirements for any later amplification by transistors, and thus the area occupied by the transistor can also be reduced significantly. This aids in the integration of the CCD-based structure into a larger silicon device incorporating several functions.

[0008] One specific application of the current invention is for use in amplifying signals taken from electrocardiogram (ECG) electrodes. One electrode is commonly used as a reference voltage, and the other electrode is used as a signal voltage. Both electrodes are attached to a patient's body, and their respective ends are connected to gates in the CCD which control the input of charge into the CCD. A charge packet equal to the difference in voltages can be created and amplified by the method as described in this invention. Alternatively, a single electrode can be used as the input to create a charge packet of a size equivalent to the voltage input from the electrode and then amplified. The difference between electrode inputs can be calculated at a later point after output from the CCD. Because the electrode connections preferably are directly inputted into the CCD, this results in a high impedance value. This is desirable to avoid any adverse reaction from the patient as a result of the electrical connection to the CCD.

Problems solved by technology

Because the electrode connections preferably are directly inputted into the CCD, this results in a high impedance value.

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